基于拆卸约束图的产品可行拆卸序列生成算法

拆卸序列生成是拆卸工艺及规划的重要内容之一。针对拆卸序列规划过程中的可行拆卸序列遗漏问题,首先阐述了拆卸约束图(disassembly constraint graph,DCG)理论,提出了一种基于干涉矩阵的邻接点判断方法,结合拆卸约束图,建立拆卸模型,给出了生成产品所有可行拆卸序列的算法。最后,给出了一个生成可行拆卸序列实例,验证了这一方法的可行性及其有效性。关键词:拆卸;拆卸序列规划;拆卸约束图;干涉矩阵     

一种基于子装配体识别的装配顺序生成

装配体表达为装配连接图，在识别子装配的基础上，给出了简化装配体装配顺序的确定方法。文中对子装配的识别原则和装配顺序、装配方向的确定等问题进行了详细的阐述。     

基于子装配体的并行装配序列规划方法研究

针对复杂产品的装配规划过程较为繁琐的难题,提出了一种基于子装配体的并行装配序列规划方法。将子装配体运用到序列生成的过程当中,通过对子装配体的识别,然后将识别后的零件进行并行序列规划,实现了优化装配序列的目的。通过实例验证,结果表明此方法比纯粹的并行化规划产生的序列少,简化了整个装配序列产生时所参与的零件数,简化了复杂产品的规划过程,提高了装配效率。     

装配/拆卸干涉矩阵的自动生成技术

讨论了基于ProEngineer三维设计模型的干涉矩阵自动生成方法。通过定义集成干涉矩阵来表达零件间装配/拆卸时的干涉关系,详细给出了产生干涉矩阵所需的零件/装配体信息提取和基于零部件运动扫掠体的干涉检查过程,采用干涉矩阵元素的二进制和十进制转换来降低计算复杂性,给出了干涉矩阵生成的算法流程并初步开发了原型系统。通过示例说明了系统的应用过程。     

基于改进干涉矩阵的机械产品拆卸序列规划

以生成正确合适的拆卸序列为目标,针对复合拆解路径问题提出改进干涉矩阵,用以表达零件之间的约束关系,以此为基础建立了干涉矩阵模型。为了避免复杂机械产品在拆卸时产生组合爆炸问题,提出了子拆卸体及其识别方法,以使得部分零件可以实现模块化拆卸。同时,引入了支撑矩阵来描述零件竖直方向的受力情况,作为拆卸中零件稳定性的判别准则。最后,文章通过机用平口钳案例验证所提出的拆卸序列生成方法的可行性。结果表明,该方法减少了生成拆卸序列的搜索工作量,有效地避免了不稳定性序列的产生。     

基于有向图子装配识别的装配序列规划

采用局部约束有向图表达装配体中的联接与装配关系;通过建立装配邻接和阻碍矩阵,采用ISM分析、紧连接分析、有向回路分析来识别子装配体;采用拓扑分层排序来生成产品装配体的可行装配序列;以减速器部分装配结构的装配序列规划验证了该方法的可行性.     

基于符号有序二叉决策图的装配序列生成技术

为提高装配序列规划求解效率和自动化水平,给出了装配体联结图模型、干涉向量和接触向量模型的有序二叉决策图描述,建立了基于符号有序二叉决策图模型及操作的可行装配序列生成技术.结合实例验证了基于有序二叉决策图的装配体模型和可行装配序列生成技术的正确性和可行性.     

基于符号有序二叉决策图的装配序列生成技术

为提高装配序列规划求解效率和自动化水平;给出了装配体联结图模型、干涉向量和接触向量模型的有序二叉决策图描述;建立了基于符号有序二叉决策图模型及操作的可行装配序列生成技术。结合实例验证了基于有序二叉决策图的装配体模型和可行装配序列生成技术的正确性和可行性。     

基于有向割集分解的装配序列生成方法

基于有向图理论,提出了装配序列规划新方法。把有向图理论引入到装配模型表达,提出了有向装配连接图模型,并给出了有向装配连接图的性质。通过对有向装配连接图的割集分解计算,实现了装配序列生成。此方法比无向割集分解方法计算量小、产生无效序列少。为进一步剔除无效序列研究了单调非线性装配意义下基于有向割集分解的装配序列生成算法,并讨论了约束的加入和表达方法。最后给出了一个装配实例,证明了算法的有效性。     

基于层次模型的人机交互装配序列生成算法研究

针对装配序列规划中组合爆炸及所生成装配序列的工程有效性不高的问题,提出了在层次模型基础上,对零件间装配关系进行人机协同量化,然后分层次、在子装配体范围内进行装配序列规划,最后结合柱塞泵的装配实例,验证了采用该方法能生成工程有效性较高的装配序列。     

Automatic Subassembly Detection from a Product Model for Disassembly Sequence Generation

The time taken for the generation of assembly or disassembly sequences is proportional to the number of components in the assembled product. For each additional component considered, the number of possible sequences to assemble (or disassemble the product) increases combinatorially. Research work had been carried out to reduce this complexity so that unfeasible assembly sequences could be discounted. A significant approach to further reduce the time for the generation of the assembly sequences is to group components together into subassemblies and then to treat these subassemblies as "individual components". This will reduce the number of components involved in the search or generation of assembly sequences, and hence reducing the sequence generation time. This paper presents a methodology for automatically extracting subassemblies from a product in order to simplify the disassembly or assembly sequence generation.     

基于拆卸Petri网和混沌粒子群的拆卸序列规划

为解决燃气涡轮发电机组虚拟拆装训练中拆卸序列规划问题,提出了基于拆卸Petri网和混沌粒子群优化算法的拆卸序列规划方法。在基本Petri网的基础上进行拓展,引入了时间元素,构建了拆卸Petri网模型;针对粒子群优化算法容易陷入局部极值的不足,将混沌寻优方法嵌入到粒子群优化算法中,结合早熟评判标准,提高粒子群算法全局寻优能力。运用上述方法,以最短时间为目标,对分配机匣的完全拆卸序列进行仿真实验,得到了符合实际操作规律,可行有效的拆卸序列。     

Mechanical Product Disassembly Sequence and Path Planning Based on Knowledge and Geometric Reasoning

A feature-based assembly model is proposed for disassembly sequence planning, and establishing a correct and practical disassembly path for the part in the product, based on geometric reasoning and knowledge. The fundamental assembly modelling strategy for a product is based on the mating features of its parts. An algorithm is introduced which uses the information provided by the mating features of parts in the product to find the candidate parts for disassembly and to carry out disassembly path planning. A complete and accurate interference checking approach is used to ensure no global collision while disassembling a part. In some cases, it cannot be implemented by geometric reasoning alone, so a set of criteria and heuristic rules based on knowledge, constraints, relationships among parts, and quantitative disassemblability assessment are used. It can also be carried out interactively by the user when necessary. The proposed method is integrated with the CAD model of the product. The user can visually disassemble the product while planning, so it is easier to carry out the disassembly planning and generate an optimal sequence.     

基于Pareto解集蚁群算法的拆卸序列规划

为提高产品拆卸序列规划的效率,分析拆卸序列规划问题中的多个优化目标平衡问题,提出一种基于Pareto解集的多目标蚁群优化算法求解此类拆卸规划问题,并给出拆卸序列的构建过程。通过利用拆卸矩阵推导拆卸可行条件,获得可以执行拆卸操作的零件及其可行的拆卸方向。通过利用零件的轴向包围盒(Axis aligned bounding boxes,AABB)计算零件的拆卸行程。考虑拆卸方向改变次数、拆卸总行程、拆卸零件数量为优化目标,通过利用蚁群算法搜索可行解并计算各个解之间的支配关系,得到Pareto解集,实现求解优化的拆卸序列,给出算法的具体步骤。最后以单杠发动机为拆卸实例,利用所提方法进行拆卸序列规划求解,通过分析试验结果,并对比典型的单目标蚁群规划算法,证明了该方法的高效性和可行性。     

基于广义轴理论的产品拆卸路径规划

如何将所有可行的拆卸路径进行紧凑、合理的表达是实现产品拆卸路径规划时首要解决的问题.为此,要对指定拆卸类型下的装配体进行有效的子装配体聚类.为在产品拆卸路径规划中实现子装配体聚类的优化,同时避免传统方法所造成的组合爆炸等问题,引用并扩展了表达零件问紧密程度的配合关系等概念,并结合对装配结构和装配过程的深入分析,提出符合工程语义的广义轴理论以及拆卸优先级修正系数等概念.在具体操作上,首先借助邻接矩阵的表达形式并结合同轴度系数函数和拆卸优先级别系数分配表等对应关系得到同轴隶属度矩阵及其修正矩阵.然后,结合模糊数学中模糊聚类分析的有关算法,得到具有传递性的模糊等价矩阵以及分属不同截距下的动态产品聚类关系图.最后,结合此关系图和拆卸优先级别系数分配表,实现子装配体的聚类优化.经验证,所提方法增强了拆卸路径划分同工程实际的一致性,同时减少了计算工作量.     

A Novel Representation Scheme for Disassembly Sequence Planning

The representation of the disassembly sequence is a key issue in maintenance planning. It involves a highly constrained combinatory problem, which is coupled with varying start and end nodes. These start and end nodes are dependent upon the nature of a maintenance task. In this paper, different representation and modelling schemes for disassembly sequence planning are first reviewed. Then, a novel representation scheme for disassembly sequence, which is generic and can be used to represent both the geometrical and precedence constraints dynamically in product disassembly, is proposed. Based on such a representation scheme, the process for the determination of possible disassembly sequences can be simplified. By taking into consideration disassembly constraints, the optimal disassembly sequence in relation to the component to be maintained (target component) can be quickly derived. This is achieved by pruning the search space of disassembly sequences, grouping related components into subassemblies, and identifying free components to facilitate disassembly oper-ations. Subsequently, the optimal disassembly sequence in relation to the target component can be obtained using genetic algorithms. In this manner, the disassembly sequences for a complex product comprising a relatively large number of components can be derived within a short time. A case study is used to illustrate the effectiveness of the representation scheme. Comparisons are made using the same case study with the AND/OR graph representation and the Petri net approach for disassembly sequence planning. The results show that the proposed representation scheme is simpler and is more efficient than the rest. ID="A1" Correspondence and offprint requests to: Dr L. P. Khoo, School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798. E-mail: mlpkhoo@nyu.edu.sg     

Disassembly Planning Based on Precedence Relations among Assemblies

An algorithm is presented that is based on a representation method for products, which lets us show, intuitively, the hierarchical relationships among components and/or assemblies of the product. This paper presents an algorithm for establishing a partial non-destructive disassembly sequence of a product. The disassembly sequence can be obtained for a component as well as for a sub-assembly (group of different components). The disassembly sequence is obtained autonomously and automatically and can be used in a flexible manufacturing system. ID="A1"Correspondance and offprint requests to: F. Torres, Department of Physics, Systems Engineering and Signal Theory, University of Alicante, Crta San Vicente s/n, PO Box 99, Alicante, Spain. E-mail: ftorres@disc.ua.es     

特征识别技术在轴类部件装配顺序规划中的应用

在总结特征识别方法的基础上 ,充分考虑轴类部件自身的形状特点 ,应用特征识别技术 ,建立了一个面向装配顺序规划的层次装配特征信息模型。给出了在无需初始化装配的情况下 ,轴类部件装配顺序规划的算法。并在MDT环境中 ,应用MCAD -API技术进行了实现     

一种面向拆卸稳定性的产品拆卸序列规划方法

针对拆卸过程稳定性问题,以及复杂产品拆卸图模型构建困难和效率低等不足,提出一种面向拆卸稳定性的拆卸序列规划方法。充分分析面向绿色制造和循环经济的拆卸的特点和原则;通过分析产品的CAD模型,构建一种集零部件类型、零部件可行拆卸方向集、零部件拆卸空间制约矩阵、零部件接触矩阵、零部件自由度约束矩阵等于一体的产品拆卸信息分析模型;提出相关拆卸优先原则和稳定性原则;给出基于拆卸过程稳定性的产品拆卸序列规划算法;通过一个完全拆卸和目标零件拆卸实例验证该算法的可行性、实用性。